Sunlight based lighting

Discussion in 'The Projects Forum' started by gautamkonda, Mar 12, 2011.

  1. gautamkonda

    Thread Starter New Member

    Mar 12, 2011

    I am an electronics enthusiast and am trying to build a circuit which senses the light from the sun. When the light intensity of the sun reduces (during sunset) below a certain level it triggers on a light.

    I was thinking of using an LDR since precision is not required here. The output of the LDR is compared with LM311 voltage comparator.

    The LM311 is then connected to a NOT gate to invert it.

    I am wondering what the output at NOT gate will be. And further can this output be used to trigger a switch for the lighting the AC bulb??

    Thanks in advance!
  2. Adjuster

    Well-Known Member

    Dec 26, 2010
    Why bother to use a NOT gate? You could reverse the operation of the comparator by swapping the connections to the comparator inputs.

    Please post a schematic of your proposed circuit.
  3. wayneh


    Sep 9, 2010
    I agree, you don't need a gate. But you will likely need a MOSFET, SSR, relay or something to switch the load. A comparator can barely sink enough current for an LED, and should be used to trigger a current switching device of some kind.

    You do know, of course, that you're building a device one can buy for a few dollars at the hardware store.